Double acting slack adjusters



May 3, 1966 H. R. BILLETER DOUBLE ACTING SLACK ADJUSTERS 5 Sheets-Sheet 1 Filed April l5, 1964 "I INVENTOR. ///gy/ f//a/a/ May 3, 1966 H. R. BILLETER DOUBLE ACTING SLACK ADJUSTERS 5 Sheets-Sheet 2 Filed April l5, 1964 IPI ,....QRI/ m5 f www W WWW/W f 2 W@ #fw Nw VQ May 3, 1966 H. R. BILLETER 3,249,183

DOUBLE ACTING SLACK ADJUSTERS May 3, 1966 H. R. BILLETER DOUBLE ACTING SLACK ADJUSTERS 5 Sheets-Sheet 4 Filed April l5, 1964 May 3, 1966 H. R. BILLETER 3,249,183'

DOUBLE ACTING SLACK ADJUSTERS Filed April 15, 1964 5 Sheets-Sheet 5 United States Patent O 3,249,183 DOUBLE ACTING SLACK ADJUSTERS Henry R. Billeter, Deerfield, Ill., assignorrto Sloan Valve Company,v Chicago, Ill., a corporation of Illinois Filed Apr.- 15, 1964, Ser. No. 359,969

15 Claims. (Cl. 18S- 202) This invention relates in general to slack adjusters for adjusting slacky in the brake rigging of a railway car, and the principal objectof 'the invention is to provide a new and improved double acting slack adjuster for automatically reducing or increasing the slack to maintain optimum brake shoe clearance.

Another object is to provide a slack adjuster of the typekhaving spinfnuts rotatable on a threaded rod in which the device utilizes fewer parts, is of lighter weight, and is constructed more compactly to it readily in all types of railway cars in position where available space is at a minimum. Y e ,y l

Another object is vto design an automatic double acting slack adjuster for -railway cars which is relatively simple and rugged in construction, protected fromv dirt and weather, positive andreliable in action, and which is relatively immunefrom false operationunder service conditions.

A.further Objectis to provide a new and improved double actingslack adjuster in`which .the usual -heavy and cumbersome restoring spring iorrestoring the parts of the vslack adjuster upon brake release, is eliminated resultingin lighter weight and reduced friction in the device.

Anothery object is to design an improved double acting slack adjuster in which vthe housing ofthe device is not shiftedor rotated when insuliicient slack 'is present as in former devices, but la :separate,triggermechanism is operated extending into lthe side of the slack adjuster to control the spin-nuts andvadjust the slack, thereby making fora moresirnple and compact arrangement of the parts of the, device. e i e With the foregoing and other objects in view, the invention consists yin `the novel construction, combination and arrangement of vparts described and illustrated hereinafter inthe accompanying drawings and pointed out in the appended claims. e e

Referring to thedrawings;

FIGURE is a plan lview illustrating a typical brake rigging arrangement on a railway car withthe slack adjusterof the invention shown therein;

FIGURE 2 is a side view of FIGURE 1;

FIGURE?)- is an end view from the left side of FIG- URE 1; y p e :V

FIGURE 4 is a cross-sectional view of a portion of the leeft hand end of the slack adjuster; e l

FIGURE 5 is a cross-sectional view of 'a portion of the lright hand end of the slack adjuster;

' vFIGURE 6 isan enlarged cross-sectional View of the center portion of thev slack'adjuster taken between points A and BA of FIGURE l; l

FIGURE 7 is a cross-sectional View taken along the line 7 -7 of FIGURE 6; c j y e FIGURE 8 isa fragmentary view of FIGURE 7; FIGURE 9 `is a plan view of the pawl plate; lFIGURElO is an enlarged right hand end view of the slack adjuster; while e l A i FIGURE 11 is a diagrammatic View of the trigger action. The improved double acting slack adjuster of the invention is adapted for installation in the brake rigging of a railway car in the usual position between the brake cylinvder push rod andbrake shoes and specifically as a center `rod connection in the brake rigging between the live lever .and the dead lever, and when so installed will automatically takeup excess slack as the brake shoes wear, and let out slack as when new brake shoes are installed, in order to maintain the travel of the brake cylinder push rod within the limits prescribed by railroad practice regulations. The present slack adjuster comprises a unitary structure including a dust proof sealed casing 5 connected at the right hand end by the clevis 6 and pivot pin 7 to the center portion of live lever 8. The upper end of live lever 8 has a pivot pin 9 for connection with a portion of the brake rigging 10 leading to the 4brake shoes (not shown). The bottom end of live lever 8 is pivoted by pin 11 to the end of push rod 12 of the brake cylinder 13, having a movable piston therein responsive to the usual brake control of the railway car in a brake application. The left hand end of the slack adjuster 5 has a tubular rod portion extending from' it which is pivoted by pin 14 to the mid-portion of dead lever 15. This lever 15 in turn is pivoted at 16 at its lower end to a portion of the brake linkage 17 leading to the brakev shoes. At its upper end the lever 15 is pivoted at 18 toma part of the railway car frame. Additionally adjacent the live lever 8 (FIGURE 3) there is an actuating lever 20 also pivoted at its upper end by pin 9 and having its lower end loosely slidable and pivoted in a slot formed in bracket 21 supported on the railway car frame. The general arrange'- ment of the foregoing elements is such that outward projection of the push rod 12 by action of the brake cylinder 13 results in the movement of the levers 8 and 15 together with the slack adjuster 5 so that braking pull is applied to linkages 10 and 17 in the direction ofv the arrows shown, to produce an application of the brakes. In other words, the distance between lever 20 and button 35 is proportional to the travel of the brake cylinder piston.

The slack adjuster 5 is preferably made of two separate hollow sections or casings 22 and 23 bolted together at gasketed flanges formed at their abutting ends as shown. One end of a tubular pull or power rod housing 24 is welded to casing 22 and movable therewith, while the other end is provided with a suitable closure and sealing means 25 slidable around the power rod 26 extending 'axially through the housing tube 24. The power rod 26 is disposed for axial shifting movement within the tube 24 as Well as housings 22 and 23. For a substantial portion of its length, within the casings, the power rod 26 is provided with non-self locking threads 30 having a high helix angle upon which a series of spin-nuts are adapted to be rotated as will be pointed out.

Extending from the right hand end of housing 23 and welded thereto is a tube 31 the other end of which is welded to the casing 32 lin which the clevis 6 is formed. The threaded power rod 26 is adapted to partially telesco-pe within the tube 31. A fixed guiding tufbe 33 is arranged'parallel to and below tube 31 and is suitably welded at one end into housing 23 and at the other end into housing 32 as shown. Axially slidable within tube 33 is a trigger tube 34 having a trigger button 35 attached to its right hand end, which button is adapted to contact the mid-portion of actuating lever 20. l The left hand end of trigger tube 34 is slidable through an opening in casing 23 and projects into the casing 22. A pair of nested compression springs 37 and 38 extend the full length Within trigger tube 34 from the button 35 to the stop Washerl 39 in casing 22. A guiding stern 40 passes axially through'the springs 37 and 38 and is fastened to the washer 39 for support. The springs normally hold and restore the trigger mechanismlinto the position as shown. v

The trigger tube 34 at its end Within housing 22 supports and carries along with it a ratchet spool control Y .s sides of trigger tube 34 and firmly anchor the control member 45 to the trigger tube 34. A pair of upstanding arms 49 and 50 straddles the threaded power rod 26 and is provided with rollers 51 and 52 engageable with opposite sides of a spool-shaped ratchet spin-nut 55, there being a relatively minute clearance provided for free rolling contact as nut 55 turns. upon the threaded rod 26 under control of the control memberv45 as will be pointed out. rotate on bearing pins 53 and 54 having support in arms 49 and 5t). To hold the bearing pins in place hollow roll pins 55 and 56 extend .through the arms 49 and 50.

One end face 57 of spool-shaped spin-nut 55 is provided with a series of ratchet teeth 58 around its peripheral area which are adapted to be'engaged by a pair of oppositely disposed pawls 59 and 60, more clearly seen in Rollers 51 and 52' Spin-nut 55 is rotatable FIGURE 9. The pawls S9 and 60 are formed in pawl K plate 61 the bottom portion of which has an opening 62 through which the trigger tube 34 extends. There is an odd number of ratchet teeth 58, for example, nine, so that only one of the pawls 59 0r 60 at a time can engage the teeth 58, thereby providing closer stepping increments of the spool-shaped spinnut 55. The pawl plate 61 is carried along with control member 45 but is rocked at its lower end on pivot point 63 formed in member 45. An

place the push rod 12 is forced outward by air pressure in the brake cylinder 13 operating live lever 8 and since the upper end of the actuating lever 20 is also pivoted at 9 together with live lever 8, and the lower end of lever 20 is slidably restrained by the bracket 21 (FIGURE 3), the levers 8 and 20 will separate angularly about pin 9. The slack adjuster being pivoted to the center of live lever 8 at pivot 7, the angular movement of both levers 8 and 20 will cause the center edge portion of actuating lever to contact the button 35 after a rcertain movement of the lever 8.v This movement is calculated so that the lower end of live lever 8 will be operated by the push rod 12 .over a movement of about `7 or 8 inches before the actuating lever 20 engages the trigger button 35. Any travel of the push rod 12 beyond this distance indicates an excess of slack in the brake linkage or in brake shoe wear. v

Assume that there is an insufficient amount of slack in the brake rigging as would be the result of the installation of new shoes for example. It would accordingly be necessary to introduce some slack in the system by increasing the overall length Yof the slack adjuster.y Upon adjustable screw 64 threaded into control member 45 has acoiled spring 65.under its head tending to urge the pawl plate 61 towards the spin-nut 55. This .is however prevented by la pair of push pins 66 and 67 projecting along opposite sides of the spin-nut 55 and adapted to engage pawl plate 61 and push the pawls 59 or 60 away from the ratchet teeth 58 under certain conditions of operation., The push pins are conveniently journaled and supported nin the hollow roll pins 55 and 56.

In addition to the ratchet spin-nut 55 the threaded power rod 26 also has two other spin-nuts 70 and 71 rotatable thereon and several friction clutch surfaces Within the housing 23 `adapted to control the rotation of these spin-nuts. One of these friction clutch surfaces 72 is formed between the end spool discr73 of spin-nut 55 and a collar or friction ring 74 threaded into the housing 23, in turn locked in place in housing 23 by the set screw 75. The adjusting spin-nut 70 is arranged on the threaded rod 26 lbetween spin-nuts 55 and 71 and is provided with an edge surface engageable with friction clutch surface 76 on collar 74 and an anti-friction roller bearing 77 pressing against bowed spring washer 78 which in turn rests against the Xed stop ring 79. The third spin-nut 71 is provided with roller bearings 80 on one side thereof resting against bowed spring washer 81 supported on a shoulder formed in casing 23. On the other side of spin-nut 71 there is a rotary disc 82 having rotary sliding t on spin-nut 71 and providing a `friction clutch surface 83 with the casy ing 23. Another friction clutch surface 84 is provided between the disc 82 and spin-nut 71. Needle thrust bearing 85 is placed on disc 82 and bears against a plurality of Belleville disc type springs 86 to normally urge the disc 82 into frictional Contact with clutch surface 83. The spin-nut 71 with clutch surface 84 is normally held in engagement by the bowed washer 81 and thrust bearing 80 as shown. In the same normal position shown the clutch surfaces 76 will be disengaged from spin-nut 78 but clutch surface 72vwill'be engaged'by spool end 73 of the-ratchet spin-nut 55.

For reasonsr well understood in the art, the maximum stroke of the brake cylinder push rod 12in response to a braking application cannot exceed 12 inches, andan optimum range of about 8 inches is selected for the slack adjuster to make its automatic adjustment for abnormal slack, which may be present in the brake rigging or linkage. The 8 inch stroke required is also made up of other elements in the system. `The various parts of the brake rigging and slack adjuster are shown in the drawings as they appear in the position with t-he brakes released and in the running position. When a brake application takes a brake application under these conditions, the slack adjuster 5 ,will initially move as a solid unit or link in the system. This occurs `because the Belleville springs 86 force ,disc 82 tightly into engagement with clutch surface 83 and spin-nut 71 with clutch surface 84 preventing rotation of spin-nut 71 on power` rod threads 30. Spinnuts 55 and .'70 are immobile at this time. Since there is insuflicient slackinthe system the brake shoes will engage the car wheels almost immediately, or before the brake cylinder piston has traveled the required distance thereby creating acertain amount of stressin the linkage and system which increases untilthe tensionof the Belleville springs 86 vis overcome thereby separating spin-nut 71 and disc 82 from clutch surfaces 83 and 84. The power rod 26 now pulls to the left while' thel casing 22 pulls to the right and as a result, the spin-nut 71 rotates on the threaded rod 30and its bearings 80 lengthening the slack adjuster. At the same timeratchet spin-nut 55 -disengages from its clutch surface 72 so both this spin-nut 55 as well as spin-nut 70 rotate on the threaded rod 26 to let out slack.

When the required amount of slack has been let out, the lever 20 contacts the trigger button :35 and causes spin-nut 55 to move to the -left allowing the spin-nut 70 to engage the clutch surface 76 thereby rigidly coupling the threaded pull rod 26 with the' slack adjuster casing. During this movement the ratchet teeth 59V of spin-nut 55 may rotate Vacross thepawls 59 and 60 on pawl plate `61 without effect. Upon release of the brakes, the gravity weight of the brake rigging together with the brake beams and shoes, restores the equipmentV to the normal position shown with the spin-nuts in anew position on the. threaded rod 26. Also during this restoring movement the push pins 66 and 67 in the control member 45 will force the pawl plate 61 away from the ratchet teeth'58 as soon as the rear end of the pins engage the threaded collar 74. It will be noted that inthe vcase of insucient slack the trigger button 35 does not contact theactuating lever until after slack is let out and that the slack let out takes place upon application of the brakes.

In the event there is an excess of slack in the system such as would be caused by wear of the shoes, loss of one or more shoes, or other causes, the brake cylinder Apush rod- 12 would be operated beyond the maximum vmember p45.' The pawl plate 61 tilts inward on its pivot 63 to move its pawls 59 and 60 toward the ratchet teeth 58 under pressure of the spring 65. The coupling spin-nut 70 engages its friction clutch surface 76 to lock the threaded rod 26 andthe casing together as a unit. The let out spin-nut 71 at this time is also in frictional engagement with clutch surface 84, and disc 71 with clutch surface 83, thus locking the parts together. As a further result of the movement of the control member 45 to the left, it spins the ratchet spin-nut 55 to the left along the threaded rod 30 by `means of the rollers 51 and 52 arranged on opposite sides of the nut 55,thereby causing the separation of spin-nut 55 and coupling nut 70 on the threaded rod 26 in accordance with the amount of excess slack. As the spin-nut 55 rotates along the threaded rod it ratchets around the pawls 59 and 60.

Upon release of the brakes the weight of the braking system restores the slack adjuster equipment, assisted by the restoring springs 37 and 38 of the trigger mech-anism. The ratchet spin-nut 55 however during this return movement is prevented from rotating because the pawls 59 or 60 are now engaging ratchet'teeth 58, and since the braking tension isk removed from the spin-nuts 70 and 71 due to the right hand inward movement of the threaded rod 26, these nuts spin on the threads to take up the excess slack until surface 72 is engaged by the ratchet spin-nut 55 to halt the further movement. The push pins 66 and 67 engage the edge of collar 74 to release the pawlv plate 61 from the ratchet teeth 58 and the control member assumes the vnormal position as shown.

From the foregoing it will be clear that when there is insufiicient'slack in the braking system and some must` Because of the absence of a powerful restoring spring the parts can be made much simpler and lighter and operate more reliably, and thel spin-nuts rotate freely with less friction. The equipment is relatively immune to shocks or transient vibrations so that false slack let out or take up cannot possi-bly occur. Should the pull rod 26 be given an inward shock or thrust, the ratchet spin-nut portion 73 would be pressed much firmer against the clutch surface 72, in addition to the force provided by the control member 45 and springs 37 and 38. Should the pull rod 26 be givena rtransient outward pull, a false let out is prevented by the spin-nut 71 and friction disc 82 engaging clutch surfaces 83v and 84 under the pressure of the strong Belleville springs 86 to hold the spin-nut stable.

Referringnow `to FIGURE 11, this shows a diagrammatic sketch of the specific sequence of operations which takes place during the relative travelvof ythe actuating lever 20 and its approach to and operationof the trigger button 35. The movement of the level 20v through the distance A occurs during the time slack is let out when sufficient pull or stress is imposed on the slack adjuster by the brake system to cause all of the spinnuts 73, 70, 71 and disc 82 to be' disengaged from their respective clutch surfaces and spin when the brakes are being applied. The small movement indicated at B (about 3&6 inch) immediately prior to the engagement of lever 20 with button 35, stops the letout 0f slack because the stress in the` system causes the spin-nut 70 to engage clutchv surface 76. The short movement indi- 'cated at C is that in which the slack adjuster is incapable of taking up slack or letting it out. The ratchet teeth 58 are disengaged from they pawls because the ratchet spin-nut 55 khas been moved only slightly and spin-nut 70 has engaged clutch surface 76. The movement indicated at Dof course is that during which slack take up occurs as the brakes are being released and ratchet spinnut 55 is rotated outward and spin-nut 70 locked.

While only a preferred embodiment of the invention has been described and illustrated in the drawings, this is not to be in the nature of limitation, and it is obvious to those skilled in the art that certain variations may be conceived within wide limits without however departing from the spirit of the invention.

What is claimed is:

1. An automatic slack adjuster including a housing, a rod reciprocal in said housing, a number of spin-nuts threadably mounted on said rod within said housing, at least one of said spin-nuts being spool-shaped, a number of clutch surfaces longitudinally spaced on sa-id housing for engagement by said spin-nuts, a trigger member slidable in said housing, a `roller carriedy by said trigger member and rotatably engageable with said spool-shaped spin-nut to move the same rotatably on said rod and linearly of said housing and rod in responseto relative longitudinal movement of said housing and trigger member, means for locking said spool-shaped spin-nut against rotation on said rod, including a ratcheting surface formed on an end face of said spool-shaped spin-nut and a ratcheting member pivotally carried -by said trigger member and having a ratcheting surface yieldingly urged toward spin-nut end face, and means for separating said ratcheting surfaces, including a stop member slidably carried by said trigger member and positioned to engage said ratcheting member when said trigger member and housing are at a predetermined relative position.

2. An automat-ic slack adjuster including a housing, a rod reciprocal in said housing, a plurality of spin-nuts in said housing and threadably mounted on said rod, a clutch surface on said housing for each of said spinnuts to lock said rod and housing against relative reciprocation upon engagement lby one of said spin-nuts, means yieldingly engaging each of said spin-nuts to urge the same toward one of said clutch surfaces, at least one of said spin-nuts being formed of two segments, the first of said segments having a first clutch surface yieldingly urged at a predetermined force ,toward engagement with one of said housing clutch surfaces, said first segment having a bore lthereinfslidably and rotatably rece'iving the second of said segments and having a second clutch surface thereon, the second of lsaid -segments being threadably mounted on said rod and having a clutch surface yieldingly urged toward said second clutch surface of said first segment at a force less than said predetermined -force.

3. An automatic slack adjuster including a housing, a rod reciprocal in said housing, a plurality of spin-nuts in said housing and threadably mounted on said rod, at least one of said spin-nuts being formed of two segments, the first of said segments having a first clutch surface yieldingly urged toward engagement with said housing, said first segment having a bore therein slidably and rotatably receiving the second of said segments and having .a second clutch surface thereon, the second of said segments being threadablvmounted on said -rod and having a clutch surface yieldingly urged toward said second clutch surface of said first segment.

4. An automatic slack adjuster including a housing,

a rod extending into said housing, first and second spinnuts threaded on said rod within said housing, a trigger member slidable in said housing and engaging said first spin-nut for linear and rotatable movement of said first spin-nut on said rod in response to relative movement of said housing and trigger member, a clutch surface in said housing, means yieldingly urging said second spin-nut into engagement with said clutch surface to lock said rod and housing against relative longitudinal movement when said first spin-nut is moved in one linear direction on said rod, a second clutch surface positioned in said housing for engagement by said first spin-nut, said rst spin-nut engaging said second spin-nut and holding said second spin-nut away from said first-named housing clutch surface against the action of said yielding means when said first spin-nut engages said second clutch surface.

5. In a slack adjuster having a housing, a rod having a threaded portion in said housing and a pair of spin-nuts linearly positionable on said rod and alternatively engaging said housing tolock said rod and housing against relative longitudinal movement, the combination therewith of a third spin-nut threaded on said rodand having a clutch surface, a clutch disc rotatable on said third spinnut and having a first clutch surface engageable with said housing and a second clutch surface engageable with said third spin-nut clutch surface, and yielding means urging said first clutch surface toward said housing and said third spin-nut clutch surface toward said second clutch surface.

6. In a slack adjuster having a housing, a rod having a threaded portion in said housing and a pair of spin-nuts linearly -positionable on said rod and alternatively engaging said housing to llock said rod and housing against relative longitudinal movement, the combination therewith of a third spin-nut threaded on said rod and having a clutch surface, a clutch disc rotatable on said third spinnut and having a first clutch surface engageable with said housing and a second clutch surface engageable with said third spin-nut clutch surface, and yielding means urging sai-d tir-st clutch surface toward said housing and said third spin-nut clutch surface toward said second clutch surface, said yielding means urging said first clutch surface toward said housing at a predetermined force and urging said third spin-nut clutch surface toward said second'clutch surface at a lesser force.

7. In a slack adjuster for use in a brake rigging, a housing, a rod having a threaded portion extending into said housing, said housing and rod being individually secured to different parts of said rigging, a spool-shaped nut threaded on said rod in said housing, a coupling spin-nut threaded on said rod in saidfhousing, a let-out spin-nut threaded on said rod in said housing, a clutch disc rotatable on said let-out spin-nut, cooperating clutch-surfaces between said housing and said let-out spin-nut and betweensaid clutch disc and said let-out spin-nut, other cooperating clutch surfaces between said housing and said spool-shaped spin-nut and between said housing and said coupling spin-nut,.yielding means urging each set of said cooperating clutch surfaces relatively into engagement with each other at varying predetermined forces, a trigger member having a control arm engaging said spool-shaped spin-nut at all positions of same and effective to move said spool-shaped spin-nut in one direction on said rod and disengage the clutch surfaces between saidhousing and said spool-shaped spin-nut in response to the presence of slack in said rigging during a brake-applying movementy of said rigging, the clutch surfaces between said coupling nut and said let-out spin-nut and said clutch disc remaining locked in engagement onl the rod during the movement of said spool-shaped spin-nut.

8. In a slack adjuster for use in a brake rigging, a housing, a rody having a threaded portion extending into said housing, said housing and rod being individually secured to different parts of said rigging, a spool-shaped nut threaded on said rod in said housing, a coupling spinnut threaded on said rod on said housing, a let-out spinnut threaded on said rod in said housing, a clutch disc rotatable on said let-out spin-nut, cooperating clutch surfaces between -said housing, spool-shaped spin-nut, between said housing and said coupling spin-nut, and between said clutch disc and letout spin-nut, yielding means urging each set of said cooperating clutch surfa-ces relatively-into engagement with each other at varying predetermined forces, a trigger member having a control arm engaging said spool-shaped spin-nut at all positions of same and effective to move said spool-shaped spin-nut in one `direction on said rod and thereby disengage the clutch surfaces between said housing and said spool-shaped spinnnt in response to the presence of slack in said rigging during a brake-applying movement of said rigging, lock means carried by said trigger control arm and Positioned to lock said spool-shaped spin-nut against rotation on said rod-upon completion of said brake-applying rigging movement, said coupling spin-nut, said clutch disc and said let-out spin-nut clutch surfaces being engagedvwith said housing clutch surfaces during said brake-applying rigging movement to lock said rod and housing against relative linear movement, said last-named clutch surfaces being disengaged by rigging stresses during brake-releasing movement Yof said rigging to permit relative linear movement of said rod and housing and to take up slack when excessive slack is present in said rigging, the housing clutch surfaces cooperating with'said spool-shaped and coupling spin-nuts and the clutch surfaces between said disc and let-out spin-nut being disengaged by brake-applying rigging movement stresses-when insufficientslack is present in said rigging.

9. In an automatic double acting slack adjuster for adjusting for variations of slack in the brake rigging of railway cars, a threaded rod and a tubular casing connected in said brake rigging and arranged t0 either take up or let-out slack, said threaded rod adapted to be shifted axially Within said tubular casing, a ratchet spinnut on said threaded rod, ycontrol means on said tubular Casing having -an actuating arm engaging said ratchet spin-nut, said control means actuated only upon brake application and when there is an excess of slack in said brake rigging, saidfactuating arm effective to rotate said ratchet spin-nut along said threaded rod a distance equal to the amount of excess slack present, cooperating pawl and ratchetmeans between said control means and said ratchet spin-nut, ineffective during rotation of said ratchet spin-nut, a coupling spin-nut on -said threaded rod, clutch means for locking said coupling spin-nut onrsaid threaded rod to prevent itfromrotating thereon during brake application and thereby to couple said threaded rod and said tubular casing together, said ratchet spin-nut being rotated in a direction away from said coupling spin-nut, and` means responsive vto release ofthe brakes for causing said control means torlock said pawl and ratchet means togetherv and prevent said `ratchet spin-nut from rotating whereby said threaded rod is shifted to take up the excess slack and said ratchet spin-nut is moved in a direction toward said coupling spin-nut.

10. In an automatic double acting slack adjuster for adjusting for variations of slack in the brake rigging of railway cars, a threaded rod and a tubular casing connected in said brake rigging and arranged to either take up or let-out slack, said threaded rod adapted to be shifted axially withinsaid tubular casing, a ratchet spin-nut on said threaded rod, control means on said tubular casing having an actuating arm engaging said ratchet spin-nut, said control means actuated only upon brake application and when there is an excess of slack in said brake rigging, said actuating arm effective to rotate said ratchet spin-nut along said threaded rod a distance equal to the amount of excess slack present, cooperating pawl and ratchet means between said control means and said ratchet spin-nut being ineffective during rotation of said ratchet spin-nut, a coupling spin-nut on said threaded rod clutch means for locking said coupling spin-nut on said threaded rod to prevent it from rotating during brake application and for coupling said threaded rod and tubular casing together, said ratchet spin-nut being rotated along said threaded rod by said actuating arm in a direction away from said coupling spin-nut, said control means operated responsive to release of the brakes for locking said pawl and ratchet means together to prevent rotation of said ratchet spinnut whereby said threaded rod is shifted along with said ratchet spin-nut in a direction towards said coupling spinnut to take up the excess slack, and movable pin means on said actuating arm engaging said pawl for disconnecting said pawl from said ratchet means when said ratchet spin-nut has been shifted to normal position.

11. In an automatic double acting slack adjuster for adjusting for variations of slack in the brake rigging of railway cars, a threaded rod and a tubular casing connected in said brake rigging and operable to either let-out or take up slack, said threaded rod adapted to move axially Within said tubular casing, a control mechanism in said `casing operable only responsive to a condition of excess slack in said brake rigging and upon brake release, a ratchet spin-nut and a coupling spin-nut normally together on said threaded rod, said control mechanism having a pair of arms straddling said threaded rod, rollers on said arms engaging opposite ends of said ratchet spinnut to move the same on said threaded rod away from said coupling spin-nut in one direction upon brake application, and in the opposite direction towards said coupling spin-nut upon brake release, and means for locking said ratchet spin-nut in only one of the directions it moves,

12. The slack adjuster as claimed in claim 11, in which the ratchet spin-nut and the control mechanisms are provided With mutual cooperating pawl and ratchet arrangements so that upon brake release the ratchet spin-nut is locked from movement on said threaded rod and said control mechanism shifts both said ratchet spin-nut and said threaded rod together to take up slack.

13. The slack adjuster as claimed in claim 11, in which the ratchet spin-nut is in the form of a spool having opposite flanged ends between which the rollers are positioned to shift the ratchet spin-nut in opposite directions.

14. The slack adjuster as claimed in claim 11, in which the ratchet spin-nut is spool shaped having opposite end anges between which the rollers are positioned to shift, the ratchet spin-nut in opposite directions, one of said anged ends being adapted to frictionally engage the tubular casing to stop the movement of said ratchet teeth thereon to lock the ratchet spin-nut on the threaded rod.

15. The slack adjuster as claimed in claim 11 in which the ratchet spin-nut and the control mechanism are provided with cooperating pawl and ratchet means arranged so that upon brake release the ratchet spin-nut is locked on said threaded rod whereby said control mechanism shifts both said ratchet spin-nut and said threaded rod in a direction towards said coupling nut, said ratchet mechanism being disengaged when said ratchet spin-nut. has been shifted into engagement with said coupling nut.

References Cited by the Examiner UNITED STATES PATENTS 2,084,989 6/1937 Browall 18S-196 2,497,343 2/1950 Carlbom 188-196 2,973,841 3/1961 McClure et al 188-196 3,177,985 4/1965 Rauglas 18S- 202 MlLTON BUCHLER, Primary Examiner.

DUANE A. REGER, Examiner. 

1. AN AUTOMATIC SLACK ADJUSTER INCLUDING A HOUSING, A ROD RECIPROCAL IN SAID HOUSING, A NUMBER OF SPIN-NUTS THREADABLY MOUNTED ON SAID ROD WITHIN SAID HOUSING, AT LEAST ONE OF SAID SPIN-NUTS BEING SPOOL-SHAPED, A NUMBER OF CLUTCH SURFACES LONGITUDINALLY SPACED ON SAID HOUSING FOR ENGAGEMENT BY SAID SPIN-NUTS, A TRIGGER MEMBER SLIDABLE IN SAID HOUSING, A ROLLER CARRIED BY SAID TRIGGER MEMBER AND ROTATABLY ENGAGEABLE WITH SAID SPOOL-SHAPED SPIN-NUT TO MOVE THE SAME ROTATABLY ON SAID ROD AND LINEARLY OF SAID HOUSING AND ROD IN RESPONSE TO RELATIVE LONGITUDINAL MOVEMENT OF SAID HOUSING AND TRIGGER MEMBER, MEANS FOR LOCKING SAID SPOOL-SHAPED SPIN-NUT AGAINST ROTATION ON SAID ROD, INCLUDING A RATCHETING SURFACE FORMED ON AN END FACE OF SAID SPOOL-SHAPED SPIN-NUT AND A RATCHETING MEMBER PIVOTALLY CARRIED BY SAID TRIGGER MEMBER AND HAVING A RATCHETING SURFACE YIELDINGLY URGED TOWARD SPIN-NUT END FACE, AND MEANS FOR SEPARATING SAID RATCHETING SURFACES, INCLUDING A STOP MEMBER SLIDABLY CARRIED BY SAID TRIGGER MEMBER AND POSITIONED TO ENGAGE SAID RATCHETING MEMBER WHEN SAID TRIGGER MEMBER AND HOUSING ARE AT A PREDETERMINED RELATIVE POSITION. 